The adenylate cyclase system of S49 lymphoma cells, sensitive to beta-adrenergic agonists and to prostaglandin E1, will be explored by genetic, biochemical, and pharmacological techniques. Variants of the S49 cell that display two stable altered phenotypes are available. One is deficient in adenylate cyclase activity; the other possesses both beta-adrenergic receptors and adenylate cyclase, but there is no response to ligand (hormone) binding; it is thus uncoupled. Attempts will be made to elucidate the molecular lesion in the uncoupled variant by analysis of membrane lipids and proteins. Physical properties of the beta-adrenergic receptor and adenylate cyclase will be compared in wild-type and invariant cells. Characteristics of ligand binding to beta-adrenergic and prostaglandin receptors will be analyzed in wild-type and in variant cells. Methods will be explored to reconstitute the hormonal response of adenylate cyclase from variants with complementary defects. For example, adenylate cyclase-deficient and uncoupled variants will be fused in the presence of cycloheximide, membrane fusion experiments will be attempted, and specific factors will be resolved and, hopefully, reconstituted into deficient particles. Further attempts will be made to select an S49 cell variant that is deficient in the beta-adrenergic receptor. If obtained, it will be valuable for the proposed studies in reconstitution. BIBLIOGRAPHIC REFERENCES: Maguire, M.E., Wiklund, R.A., Anderson, H.J., and Gilman, A.G. Binding of 125I-iodohydroxybenzylpindolol to putative Beta-adrenergic receptors of rat glioma cells and other cell clones. J. Biol. Chem. 251 1221-1231 (1976). Maguire, M.E., Van Arsdale, P.M., and Gilman, A.G. An agonist-specific effect of guanine nucleotides on binding to the Beta-adrenergic receptor. Mol. Pharm. 12 335-339 (1976).